Thermochemistry of solvation and complexation in the Cu(NO3)2-water-ethanol-L-α-alanine system at 298.15 K

The heats of mixing of aqueous solutions of copper(II) nitrate and sodium alaninate and the heats of dilution of an aqueous solution of sodium alaninate in water-ethanol mixtures were calorimetrically measured at 298.15 K. The enthalpies of transfer of α-alaninate from water into water-alcohol mixtures and the standard molar enthalpies of the reaction of copper(II) complexation with α-alaninate ion in the mixtures under study are calculated. The resulting enthalpy parameters are compared with those of the similar system containing synthetic β-alanine, which was studied earlier.     

Thermochemical study of complexation and solvation in β-alanine-Cu(NO3)2-water-ethanol system: 1. Enthalpy characteristics of complexing copper(II) Ion with β-alanine

The heats of the reaction between copper(II) nitrate and sodium alaninate and the heats of dilution of Cu(NO₃)₂ solution in aqueous ethanol have been measured at 298 K using calorimetry. The standard molar enthalpies of the reaction of copper(II) complexing with alaninate ion in solvents of various compositions have been calculated. The complexing process in ethanol is more exothermic than that in water. The role of solvation effects in the thermodynamics of formation of amino acid complexes has been discussed.     

Solubilities and solvation of bis-(2,2′-bipyridyl)- and bis-(1,10-phenanthroline)dicyanoiron(II) in alcohols

Summary Solubilities of bis-(2,2-bipyridyl)- and bis-(1,10-phenanthroline)dicyanoiron(II) are reported for a range of primary aliphatic alcohols, from MeOH to 1-decanol. The established trends are compared with those for other solutes, and for the title compounds in H₂O-alcohol solvent mixtures.     

Phenyltellurenyl halide complexes of ruthenium and rhenium (CO)2RuBr2(PhTeBr)2 and (CO)3Re(PhTeI)3(μ3-I): Synthesis and crystal and molecular structures

Reactions of Ru₃(CO)₁₂ with PhTeBr₃ and of Re(CO)₅Cl with PhTeI in benzene give the stable complexes (CO)₂RuBr₂(PhTeBr)₂ (I) and (CO)₃Re(PhTeI)₃(μ³-I) (II) containing two and three ligands PhTeX (X = Br or I), respectively. The bonds between these ligands and the central metal atom are fairly shortened (on average, Ru-Te, 2.608 ?; Re-Te, 2.7554(12)-2.7634(13) ?). The Te-X bonds in the ligands PhTeBr (2.5163(5) ?) and PhTeI (2.7893(15) ?) are not lengthened appreciably. In complex II, the iodide anion is not coordinated by rhenium, yet being attached through weak secondary bonds to three Te atoms of the three ligands PhTeI.     

Pyridine-2-thione (pySH) derivatives of silver(I): Synthesis and crystal structures of dinuclear [Ag2Cl2(μ-S-pySH)2(PPh3)2] and [Ag2Br2(μ-S-pySH)2(PPh3)2] complexes

Reaction of silver(I) halides with PPh₃ in acetonitrile and then with pyridine-2-thione (pySH) chloroform (1:1:1 molar ratio) has yielded sulfur bridged dimers of general formula, [Ag₂X₂(μ-S-pySH)₂(PPh₃)₂] (X = Cl, 1, Br, 2). Both these complexes have been characterized using analytical data, NMR spectroscopy and single crystal X-crystallography. The central Ag₂S₂ cores form parallelograms with unequal Ag–S bond distances (2.5832(8), 2.7208(11) Å) in 1 and (2.6306(4), 2.6950(7) Å) in 2, respectively. The Ag?Ag contacts of compounds 1 and 2 are 3.8425(8) and 3.8211(4) Å, respectively. The angles around Ag (in the range 87.19(2)–121.71(2)° in 1 and 87.81(2)–121.53(2)° in 2) reveal highly distorted tetrahedral geometry. There are inter dimer π–π stacking interactions between pyridyl rings (inter ring distances of 3.498 and 3.510 Å in complexes 1 and 2, respectively). The solution state ³¹P NMR spectroscopy has shown the existence of both monomers and dimers. The studies reveal relatively weaker intramolecular –NH?Cl hydrogen bonding in case of AgCl vis-à-vis that in CuCl which favored both a monomer and a dimer with AgCl, and only a monomer with CuCl.     

Synthesis and X-ray investigation of novel Fe and Mn phenyltellurenyl-halide complexes: (CO)3FeBr2(PhTeBr), (η-C5H5)Fe(CO)2(PhTeI2) and CpMn(CO)2(PhTeI)

New complexes of transition metals with organotellurium halide ligands are reported. Iodination of [CpMn(CO)₂]₂(μ-Ph₂Te₂) leads to the Te-Te bond cleavage and formation of CpMn(CO)₂(PhTeI). Oxidative addition of PhTeBr₃ to Fe(CO)₅ gives the monomeric complex (CO)₃FeBr₂(PhTeBr) which is isostructural with the recently reported (CO)₃FeI₂(PhTeI). Insertion of phenyltellurenyl iodide (PhTeI) into the Fe-I bond of CpFe(CO)₂I forms CpFe(CO)₂(TeI₂Ph). Molecular structures of the reported complexes were determined by single-crystal X-ray diffraction analysis (XRD). A considerable shortening of metal-tellurium distances is observed.     

CdS formation upon decomposition of Cd(n-BuOCS2)2 in EtOH and DMF and the crystal structure of Cd(Ph3P)(n-BuOCS2)2 · Ph3P

The thermal decomposition of the chelate Cd(n-BuOCS₂)₂ (I) in EtOH and DMF, either in the absence or in the presence of Ph₃P, yields finely disperse CdS particles. Mixed-ligand complex Cd(Ph₃P)(n-BuOCS₂)₂ (II) has been synthesized. Cd(Ph₃P)(n-BuOCS₂)₂ · Ph₃P (III) single crystals have been grown. By X-ray crystallography, the crystal structure of III is built of [Cd(Ph₃P)(n-BuOCS₂)₂] mononuclear complex molecules and uncoordinated Ph₃P molecules, which reside inside channels formed by complex II molecules. The coordination polyhedron around a Cd atom is a tetragonal pyramid where the base is formed by the four S atoms of the two bidentate chelating ligands n-BuOCS₂⁻ and the P atom of the Ph₃P ligand is at the axial vertex. In the structure of III, there are supramolecular assemblies of two complex II molecules.     

Formation of Co nanoparticles in the process of thermal decomposition of the cobalt complex with hexamethylenetetramine (NO3)2Co(H2O)6(HMTA)2 · 4(H2O)

The thermal decomposition of the cobalt complex with hexamethylenetetramine (NO₃)₂Co(H₂O)₆(HMTA)₂ · 4(H₂O) was studied by the methods of differential thermal analysis, thermogravimetry, mass spectrometry, X-ray diffraction analysis, and by the magnetic method. It was established that the thermal decomposition of the complex in a current of an inert gas is accompanied by a pronounced exothermic process and formation of Co nanoparticles. It was shown that the kinetics of this process and the chemical nature of the decomposition products depend on the initial density of the sample under study.     

Unsaturation in binuclear cyclopentadienylchromium carbonyl thiocarbonyls: Viability of (η-C5H5)2Cr2(CS)2(CO)3 in contrast to (η-C5H5)2Cr2(CO)5

The cyclopentadienylchromium carbonyl thiocarbonyls Cp₂Cr₂(CS)₂(CO)_n (n = 4, 3, 2, 1) have been studied by density functional theory using the B3LYP and BP86 functionals. The lowest energy Cp₂Cr₂(CS)₂(CO)₄ structure can be derived from the experimentally characterized unbridged Cp₂Cr₂(CO)₆ structure by replacing the two terminal carbonyl groups furthest from the Cr-Cr bond with two terminal CS groups. The two lowest energy Cp₂Cr₂(CS)₂(CO)₃ structures have a single four-electron donor η²-μ-CS group and a formal Cr-Cr single bond of length ∼3.1 Å. In contrast to the carbonyl analogue Cp₂Cr₂(CO)₅ these Cp₂Cr₂(CS)₂(CO)₃ structures are viable with respect to disproportionation into Cp₂Cr₂(CS)₂(CO)₄ and Cp₂Cr₂(CS)₂(CO)₂ and thus are promising synthetic targets. The lowest energy Cp₂Cr₂(CS)₂(CO)₂ structures have all two-electron donor CO and CS groups and short CrCr distances around ∼2.3 Å suggesting the formal triple bonds required to give the chromium atoms the favored 18-electron configurations. These Cp₂Cr₂(CS)₂(CO)₂ structures are closely related to the known structure for Cp₂Cr₂(CO)₄. In addition, several doubly bridged structures with four-electron donor η²-μ-CS bridges are found for Cp₂Cr₂(CS)₂(CO)₂ at higher energies. The global minimum Cp₂Cr₂(CS)₂(CO) structure is a triply bridged triplet with a CrCr triple bond (2.299 Å by BP86). A higher energy singlet Cp₂Cr₂(CS)₂(CO) structure has a shorter Cr-Cr distance of 2.197 Å (BP86) suggesting the formal quadruple bond required to give each chromium atom the favored 18-electron configuration.     

Sandwich-type Uranium-Substituted of Bismuthotungstate: Synthesis and Structure Determination of [Na(UO2)2(H2O)4(BiW9O33)2]13?

The sandwich-type [Na(UO₂)₂(H₂O)₄(BiW₉O₃₃)₂]¹³⁻ uranium (VI) has been synthesized by reacting the trivacant species of B-α-[BiW₉O₃₃]⁹⁻ with and investigated by IR and UV–Vis spectroscopy, and elemental analysis. The X-ray single crystal analysis was carried out on Na₁₃[Na(UO₂)₂(H₂O)₄(BiW₉O₃₃)₂] · 33H₂O (I) which crystallizes in the orthorhombic system, space group Pna2₁ with a = 33.8454(19) ?, b = 21.1484(12) ?, c = 13.2403(7) ?, α = 90°, β = 90°, γ = 90°, and Z = 4. The polyanion consists of two lacunary B-α-[BiW₉O₃₃]⁹⁻ groups which sandwich two uranyl cations and one sodium cation. The uranium atoms adopt distorted pentagonal–bipyramidal coordination, achieved by two equatorial bonds to each BiW₉O₃₃ unit and one external water ligand. The coordination of each uranium atom is evident by the shift of ν_as(W–O_b–W) and ν_as(Bi–O) stretching vibrational bonds. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Oxidative addition of the Mo-Cl bond to the Pt0 complex. Synthesis and structure of Cp′Mo(μ-CO)2(C2Ph2)Pt2(PPh3)2(CO)Cl

A reaction of Cp′Mo(CO)₃Cl(Cp′ = MeC₅H₄) with (PPh₃)₂Pt(C₂Ph₂) gave the heterometallic cluster Cp′Mo(μ-CO)₂(C₂Ph₂)Pt₂(PPh₃)₂(CO)Cl (I) as the sole product. According to X-ray diffraction data, complex I contains single Pt-Mo bonds (2.7962(5) and 2.7699(5) ?) but no Pt-Pt bond (Pt…Pt 2.9746(3) ?). The coordinated diphenylacetylene molecule forms two Pt-C σ-bonds (2.054(6) and 2.083(5) ?) and a π-bond to the Mo atom (Mo-C 2.265(6) and 2.272(5) ?; C≡C 1.387(8) ?). Original Russian Text ? A.A. Pasynskii, I.V. Skabitskii, Yu.V. Torubaev, S.S. Shapovalo, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 410–413.     

Stepwise addition of CuBr at [(dtc)2Mo2(S)2(μ-S)2] (dtc=diethyldithiocarbamate): syntheses and crystal structures of two Mo/Cu/S clusters [(dtc)2Mo2(μ3-S)(μ-S)3(CuBr)] and [(dtc)2Mo2(μ3-S)4(CuBr)2]

Reactions of [(dtc)₂Mo₂(S)₂(μ-S)₂] with one or two equivalents of CuBr in CH₂Cl₂ afforded two new heterobimetallic sulfide clusters, [(dtc)₂Mo₂(μ₃-S)(μ-S)₃(CuBr)] (1) and [(dtc)₂Mo₂(μ₃-S)₄(CuBr)₂] (2). Both compounds were characterized by elemental analysis, IR, UV-vis and X-ray analysis. Compound 1 contains a butterfly-shaped Mo₂S₄Cu core in which one CuBr unit is coordinated by one bridging S and two terminal S atoms of the [(dtc)₂Mo₂(S)₂(μ-S)₂] moiety. In the structure of 2, one [(dtc)₂Mo₂(S)₂(μ-S)₂] moiety and two CuBr units are held together by six Cu-μ₃-S bonds, forming a cubane-like Mo₂S₄Cu₂ core.     

Hydrothermal synthesis and crystal structures of new uranyl oxalate hydroxides: α- and β-[(UO2)2(C2O4)(OH)2(H2O)2] and [(UO2)2(C2O4)(OH)2(H2O)2]·H2O

Two modifications of the new uranyl oxalate hydroxide dihydrate [UO₂)₂(C₂O₄)(OH)₂(H₂O)₂] (1 and 2) and one form of the new uranyl oxalate hydroxide trihydrate [(UO₂)₂(C₂O₄)(OH)₂(H₂O)₂]·H₂O (3) were synthesized by hydrothermal methods and their structures determined from single-crystal X-ray diffraction data. The crystal structures were refined by full-matrix least-squares methods to agreement indices R(wR)=0.0372(0.0842) and 0.0267(0.0671) calculated for 1096 and 1167 unique observed reflections (I>2σ(I)), for α (1) and β (2) forms, respectively and to R(wR)=0.0301(0.0737) calculated for 2471 unique observed reflections (I>2σ(I)), for 3. The α-form of the dihydrate is triclinic, space group , Z=1, a=6.097(2), b=5.548(2), , α=89.353(5), β=94.387(5), γ=97.646(5)°, , β-form is monoclinic, space group C2/c, Z=4, a=12.180(3), b=8.223(2), , β=95.817(4), . The trihydrate is monoclinic, space group P2₁/c, Z=4, a=5.5095(12), b=15.195(3), , β=93.927(3), . In the three structures, the coordination of uranium atom is a pentagonal bipyramid composed of dioxo UO₂²⁺ cation perpendicular to five equatorial oxygen atoms belonging to one bidentate oxalate ion, one water molecule and two hydroxyl ions in trans configuration in 2 and in cis configuration in 1 and 3. The UO₇ polyhedra are linked through hydroxyl oxygen atoms to form different structural building units, dimers [U₂O₁₀] obtained by edge-sharing in 1, chains [UO₆]_∞ and tetramers [U₄O₂₆] built by corner-sharing in 2 and 3, respectively. These units are further connected by oxalate entities that act as bis-bidentate to form one-dimensional chains in 1 and bi-dimensional network in 2 and 3. These chains or layers are connected in frameworks by hydrogen-bond arrays.     

Diverse coordination of two ligands in ferromagnetic [Cu(μ-HCO2)2(3-pyOH)]n and [Cu2(μ-HCO2)2(μ-3-pyOH)2(3-pyOH)2(HCO2)2]n

Two novel polynuclear complexes with methanoate anions and 3-hydroxypyridine ligands [Cu(μ-HCO₂)₂(3-pyOH)]_n (1) and [Cu₂(μ-HCO₂)₂(μ-3-pyOH)₂(3-pyOH)₂(HCO₂)₂]_n (2), respectively, were synthesized and characterized. The central copper atom in 1 is surrounded by four methanoates and a 3-pyOH molecule, forming a square-pyramidal CuO₃NO chromophore. All the methanoates are bidentate and serve as bridges between the adjacent copper ions via syn-anti and anti–anti coordination. The basal square coordination axes are formed by O(syn), N(3-pyOH) (1.974(2), 2.016(2) Å) and O(anti), O(anti) (1.945(2), 1.960(2) Å), while the third O(anti) (2.247(2) Å) is on the top of the pyramid. A ferromagnetic transition with an exchange constant 2J/k_B = 9.2 cm⁻¹ is found for 1 below 20 K. This interaction probably takes place through two syn-anti methanoates extended in a chain through the 2D structure. On the other hand, two monoatomic Cu–O–Cu intra-dinuclear asymmetric (1.986(2), 2.415(2) Å) bridges of two methanoates in [Cu₂(HCO₂)₄(3-pyOH)₄] (2) are present. An elongated distorted octahedral coordination sphere around each copper(II) atom is completed by an additional monodentate terminal methanoate (1.975(2) Å), two N-coordinated 3-pyOH (2.005(2), 2.002(2) Å) and the third weakly O-coordinated 3-pyOH (2.732(2) Å). Although a shorter Cu?Cu distance is noticed in 2 than in 1 (4.690(1) Å 1, 3.442(1) Å 2), much weaker ferromagnetism is found in 2.     

Synthesis and characterization of [MCl2(nPr-N(Ph2P)2] (M?=?Pt, Pd) complexes and hydroformylation of 1-octene using [PtCl2(R-N(Ph2P)2)] (R?=?benzyl, 2-picolyl, nPr) complexes

The synthesis and characterization of platinum(II) and palladium(II) complexes of the type [PtX₂( ⁿ Pr-N(Ph₂P)₂)] (X = Cl, I) and [PdCl₂(R-N(Ph₂P)₂)] {R =  ⁿ Pr, p-OMe(C₆H₄)} containing aminodiphosphine P,P-bidentate ligands is described. Complexes of the type [PtCl₂(R-N(Ph₂P)₂)] (where R = benzyl, 2-picolyl and ⁿ Pr) catalyzed the hydroformylation of 1-octene, albeit at low activities and slightly elevated regioselectivities toward the linear aldehyde, when compared with analogous compounds containing small bite angles.     

Specifics of pyrohydrolytic and solid-phase syntheses of solid solutions in the (MgGa2O4)x(MgFe2O4)1 ? x system

This work demonstrates the possibility of preparing solid solutions in the (MgGa₂O₄) _x (MgFe₂O₄)_{1 − x} system by pyrohydrolytic and solid-phase methods. It is shown that the products obtained have different specific surface areas depending on the ratio between metal nitrates and citric acid. The composition dependence of the unit cell parameter deviates considerably from the Vegard’s rule. The compounds obtained are found to be stable up to 300°C, which makes them candidate materials for electronics.     

Thermoanalytical and mass spectrometric study of Ni(iso-Bu2PS2)2 and NiL(iso-Bu2PS2)2 (L = 2,2′-Bipy, Phen). Saturation vapor pressure over the Ni(iso-Bu2PS2)2 chelate

The thermal behaviors of the chelate Ni(iso-Bu₂PS₂)₂ (I) and the mixed-ligand complexes Ni(2,2′-Bipy)(iso-Bu₂PS₂)₂ (II) and Ni(Phen)(iso-Bu₂PS₂)₂ (III) in air are reported. These compounds can pass into the gas phase, as was demonstrated by vacuum sublimation for I and by vacuum distillation for II and III in a gradient furnace. The mass spectra of I–III are presented and discussed. The temperature dependence of the saturation vapor pressure over I and ΔH _T ⁰ and ΔS _T ⁰ and of evaporation of I determined by the vapor transport method are reported.     

Synthesis and vibrational spectra of copper(II) and erbium(III) complexes with 2-[2′-(oxymethyldiphenylphosphinyl)phenyldiazenyl]-4- tert -butylphenol (HL) [CuL2] · 2H2O and Er(NO3)2 · 2 HL · 2H2O. Crystal structure of [CuL2] · 2H2O

The syntheses of the complex copper salt CuL₂ · 2H₂O (I) and the erbium nitrate complex Er(NO₃)₃ · 2HL · 2H₂O (II) (HL is 2-[2′-(oxymethyldiphenylphosphinyl)phenyldiazenyl]-4-tert-butylphenol) have been described. Basic vibrational frequencies in the IR spectra of I and II have been interpreted. The crystal structure of I has been determined by X-ray crystallography: the crystals are monoclinic, a = 15.157(3) ?, b = 17.080(2) ?, c = 22.451(9) ?, β = 106.09(3)°, V = 5584(3) ?³, Z = 4, space group C2/c, R = 0.0546 (for 1152 reflections with I > 2σ(I)). The coordination polyhedron of the copper atom (symmetry C ₂) can be described as a symmetrically elongated square bipyramid (4+2). The basic square of the Cu polyhedron is formed by the oxygen atom of the substituted phenol and one of the nitrogen atoms of the azo group of each of the two deprotonated ligands L⁻ (Cu-N, 1.969(6) ?; Cu-O, 1.899(5) ?). The angles between the opposite O and N atoms are 157.6°, and the other equatorial angles are in the range 90.6°–95.9°. The axial positions are occupied by the anisole O(2) and O(2A) atoms (Cu-O, 2.737(6) ?, the O(2)Cu(1)O(2A) angle, 132.3°). In the crystal of I, complex molecules and water molecules of crystallization are combined by a system of hydrogen bonds. IR spectra show that, in complex II, as distinct from compound I, the HL ligand is coordinated to the erbium atom through the phosphoryl oxygen atom. Original Russian Text ? A.Yu. Tsivadze, L.Kh. Minacheva, I.S. Ivanova, V.E. Baulin, E.N. Pyatova, V.S. Sergienko, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 4, pp. 601–607.     

Functionalization of linear and cyclic siloxanes and a dendritic carbosilane with (η-C5H5)Fe(CO)2Si(CH3)2CHCH2 via hydrosilylation reaction

A series of multimetallic systems containing silicon-linked cyclopentadienyl dicarbonyl iron moieties including carbosilane dendrimers and cyclic and polymeric siloxanes have been prepared using hydrosilylation reactions. For this purpose the vinyl-substituted silyliron complex (η⁵-C₅H₅)Fe(CO)₂Si(CH₃)₂ CHCH₂ (1) was prepared by salt elimination reaction between Na[(η⁵-C₅H₅)Fe(CO)₂] and ClSi(CH₃)₂CHCH₂ and fully characterized. Hydrosilylation reaction of 1 with the appropriate Si-H functionalized molecules in the presence of Karstedt catalyst afforded the novel silyl carbonyl iron-functionalized cyclotetrasiloxane 2, dendrimer 3 and copolymer 4, in which the organometallic units are attached to the silicon-based frameworks through a two-methylene flexible spacer. The electrochemical behaviour of compounds 1-4 has been examined in dichloromethane, tetrahydrofuran and acetonitrile solutions using cyclic voltammetry.